Jan., 1922] NICHOLS METHODS OF HEALING IN ALGAL CELLS 
19 
in the Biological Laboratory at South Harpswell, Maine. The writer 
wishes to express her appreciation to the directors, Dr. J. S. Kingsley and 
Dr. J. L. Conel, for the interest and kindness shown during the summers 
of 1919 and 1920. 
Any form that will live under cultural conditions can be treated by the 
following methods. This study is confined to Nitella, Chara, and a few 
of the coarser filamentous algae. 
Methods 
The material was mounted in water on a slide and punctured free-hand 
under a low-power objective. In order to locate a given puncture readily 
in Nitella and Chara, the distance of the injury from a given node was 
recorded; in the filamentous forms every alternate cell was punctured. 
After puncturing, the material was grown in small culture dishes; and 
careful daily observations were recorded for a month. It was found that 
punctures made free-hand, with a steel needle ground to a very fine point, 
gave satisfactory results. This method did not require the time necessary 
for the more elaborate technique with the Barber pipette holder. In 
puncturing a large number of cells, punctures of all sizes and depths were 
obtained. The amount of internal disturbance was estimated by the 
amount of protoplasm lost and by the movement of the granules in the 
interior of the cell. 
Observations 
Vaucheria. The wall of Vaucheria consists of a thin, resistant membrane 
which is so very pliable that it is difficult to puncture it without injury to 
the remainder of the filament. If the filament is very turgid, a quick, 
sharp thrust of the needle will penetrate the- wall successfully. The pro- 
toplasm is somewhat viscous and the flow is slight. The protruding pro- 
toplasm does not diffuse into the water, but forms a globular mass filled with 
plastids. 
In the nine filaments studied the punctured portion was not separated 
later by a septum from the main thallus, but healed normally. 
The delicate character of the plants and the fact that the readjustment 
of the plastids, as described by Klemm ('94), renders it very difficult to locate 
the injury after twenty-four or forty-eight hours were the determining 
reasons for not continuing the study of this form. 
Cladophora. Both marine and fresh-water forms of Cladophora were 
studied. The cell just beneath a branch was selected for a base, and from 
this base every alternate cell was punctured both in the main axis and in 
the branch. In the two or three species experimented with, the puncture 
healed readily, but the later response to the internal disturbance was so 
unusual that I have reserved this and allied forms for later study. 
Chara. In Chara the leaves and cortical cells from the growing point 
to the mature nodes were punctured. Unless the puncture was very small 
